<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            margin: 0;
            height: 100vh;
            display: flex;
            justify-content: center;
            background-color: #000;
            align-items: center;
        }



        @property --direction {
            syntax: "<angle>";
            initial-value: 0deg;
            inherits: false;
        }

        .card {
            height: 300px;
            width: 200px;
            border-radius: 8px;
            color: red;
            font-size: 2rem;
            background-image: linear-gradient(var(--direction), #5ddcff, #3c67e3 43%, #3d2068);
            animation: rotate 2s linear infinite;
        }

        @keyframes rotate {
            to {
                --direction: 360deg
            }
        }
    </style>
</head>

<body>
    <div class="card">
    </div>
</body>

</html>